How to set content size of UIScrollView dynamically

Question

I got question about UIScrollview.

The story is I have a UIView named ChartsView which I re-draw it myself by override method drawRec

Answer 1

swift (2.0)

@IBOutlet weak var btnLatestButton: UIButton!

override func viewDidLoad() {
    super.viewDidLoad()

    let height = btnLatestButton.frame.size.height
    let pos = btnLatestButton.frame.origin.y
    let sizeOfContent = height + pos + 10
    scrollview.contentSize.height = sizeOfContent

}

Above ofcourse is when you just have a fixed amount of views on your scrollview. IOS Rocks method is available but was not good for me, created more space then I needed.

    let lastView : UIView! = scrollview.subviews.last
    let height = lastView.frame.size.height
    let pos = lastView.frame.origin.y
    let sizeOfContent = height + pos + 10
    scrollview.contentSize.height = sizeOfContent

Answer 2

This is an extension written on Swift 3

extension UIScrollView {
    func updateContentViewSize() {
        var newHeight: CGFloat = 0
        for view in subviews {
            let ref = view.frame.origin.y + view.frame.height
            if ref > newHeight {
                newHeight = ref
            }
        }
        let oldSize = contentSize
        let newSize = CGSize(width: oldSize.width, height: newHeight + 100)
        contentSize = newSize
    }
}

Answer 3

Try this -

- (void)viewDidLoad
    {
        [super viewDidLoad];

// not this way. it's fixed size.....
        ChartsView *chartsView = [[ChartsView alloc]initWithFrame:CGRectMake(0, 0, 320, 800)]; 

        //self.scrollView.contentSize = chartsView.frame.size;
        [self.scrollView setContentSize:CGSizeMake(chartsView.frame.size.width, chartsView.frame.size.height)];
        [self.scrollView addSubview:chartsView];

    }

Answer 4

override func viewDidAppear(_ animated: Bool) {
    var height: CGFloat
    let lastView = self.scrollView.subviews[0].subviews.last!

    let lastViewYPos = lastView.convert(lastView.frame.origin, to: nil).y  
    let lastViewHeight = lastView.frame.size.height

    height = lastViewYPos + lastViewHeight
    scrollView.contentSize.height = height
}

Answer 5

One more easy way

- (void)viewDidLoad
{
    float sizeOfContent = 0;
    UIView *lLast = [scrollView.subviews lastObject];
    NSInteger wd = lLast.frame.origin.y;
    NSInteger ht = lLast.frame.size.height;

    sizeOfContent = wd+ht;

    scrollView.contentSize = CGSizeMake(scrollView.frame.size.width, sizeOfContent);
}

Answer 6

It is not 100% guaranteed that the last object in scrollView.subviews array will return the highest y-origin object in your scroll view. The subviews array is arranged by Z-Index (i.e the last object in the subviews array will be the object stacked the highest and will be the top-most subview in the scroll view's subviews. Instead it is more accurate to use a basic sort function to iterate through the subviews and get the object with the highest y-origin.

Swift 4

extension UIScrollView {
    func updateContentView() {
        contentSize.height = subviews.sorted(by: { $0.frame.maxY < $1.frame.maxY }).last?.frame.maxY ?? contentSize.height
    }
}

Usage (in viewDidLayoutSubviews or whenever your content size updates):

myScrollView.updateContentView()